Use derived variable size for memcpy

Change-Id: I032fb9b56ed9c9b0abf0910225151a6c8b9aa8e4

av1/common/reconintra.c

@@ -464,11 +464,12 @@ static void build_intra_predictors_high(const MACROBLOCKD *xd,
   if (extend_modes[mode] & NEED_ABOVE) {
     const int need_right = !!(extend_modes[mode] & NEED_ABOVERIGHT);
     if (n_top_px > 0) {
-      memcpy(above_row, above_ref, n_top_px * 2);
+      memcpy(above_row, above_ref, n_top_px * sizeof(above_ref[0]));
       i = n_top_px;
       if (need_right && n_topright_px > 0) {
         assert(n_top_px == bs);
-        memcpy(above_row + bs, above_ref + bs, n_topright_px * 2);
+        memcpy(above_row + bs, above_ref + bs,
+               n_topright_px * sizeof(above_ref[0]));
         i += n_topright_px;
       }
       if (i < (bs << need_right))

test/convolve_test.cc

@@ -378,7 +378,7 @@ class ConvolveTest : public ::testing::TestWithParam<ConvolveParam> {
     memcpy(output_ref_, output_, kOutputBufferSize);
 #if CONFIG_AOM_HIGHBITDEPTH
     // Copy 16-bit pixels values. The effective number of bytes is double.
-    memcpy(output16_ref_, output16_, 2 * kOutputBufferSize);
+    memcpy(output16_ref_, output16_, sizeof(output16_[0]) * kOutputBufferSize);
 #endif
   }